Delivery Calculation for Joomla3 and Joomshopping

You need to write a plugin for calculating the cost of delivery.
Joomla 3+ is a component of the Joomshopping online store.
The calculation should be carried out automatically for 3 delivery services:
Russian Post, EMS Russian Post, Pony Express
The goods will be specified characteristics in the form of warehouses of availability of goods.
Accordingly, having cities (stocks availability by characteristics of goods) in which there is this product, it is necessary to calculate the cost to the city of the client.
Example of the application:
Goods No. 1 are in warehouses A and B (there is no warehouse thereof),
Goods No. 2 are in warehouses A and B (there is no such thing in the warehouse).
The customer puts both goods in the Joomshopping basket, fills in the registration fields and the delivery address (standard Joomshopping functions), then goes to the shipping calculation page.
Delivery should be calculated for each item (which is in the basket), from each warehouse where the item is to the delivery address (which the customer specified).
Conclusion:
1 (minimum) delivery price for each delivery provider is displayed. In total, 3 delivery prices will be displayed for each product, the customer ticks against the delivery options of interest (for each product, you can choose only one delivery option), the delivery price is added to the order and the customer goes to payment (the payment plugin is already worth it) All!

All discussions are conducted via Skype only.
Payment for e-money, card, etc.
No prepayment! Payment is only upon completion, after testing!